Method of treating roadways.



S. E. FINLEY. METHOD 0F TREATING ROADWAYS. APPUCATION FILED r.15.1915.

1 ,1 92.17 8. Patented J uly 25, 1916.

jane/n @m ff M SAM EVERETT FINLEY, OF ATLANTA, GEORGIA.

METHGD OF TREATING ROADWAYS.

Specification of Letters Patent.

lat exited July 25, 191 6.

Application led February 15, 1915. Serial No. 8,370.

invented certain new and useful improvements in Methods ot' Treatingvlioatlvvays;

.and l do herelrv declare the following to be a full. clear. and exactdescription otl the invention. such as will enable others .skilled inthe. art to which it appertainsv to malte and use the same.

'This invent-ion relates to the surface treatment of roadwaysT andhas-for its object to provide the novel method ol' treating roadwavfs.hereinafter described.

-lt has been found in practice that when a roadwayv is treated withheaviP bituminous.A products. for the purpose of preservingr the road'surface and render-iner the same wearresisting. thel bituminous productscannot be inade to bond or unile with the particles ot" the. roadway, asthere is always a sufficient amount of dust and loose particles adheringt0 the stone to actas a separator between the stone proper and theheavyv bitumen. This is true, regardless of how carefully the Stone,

may be crushed or graded. This condition i not only exists in"pcm-tration macadam7 surface a portion of sand and cement which willprobably7 have sutlicient eementing values to hold them together, butthis portion of the. sand so brought to the, surface 1s .not as richwith cement as the lower portion i of the roadway, so that a thin sheetor scalo at the road surface results. which is susceptible to crackingror separating from the harder and more lirinly united base portion. Nomatter how carefully this` surface may be swept or cleaned prior to theapplication of a heav)v bitumen. it hasl been found that a Lmrd unioncannot be obtained, as a thin film of dust or foreign matter will alwaysremain to act as a separator between the heavy liquid bitumen and thelroad surface. This is also true of practically all types of roadways orstreet surfaces, includingr roads eolistructed of gravel` water-boundmacadam and the like. A lighter bitmnen. however, will penetrate theabrive-mentioned film of dust, but a. light bitumen does not possessthe.

necessary preservinpr and tement-ing values.

as it conta-ins a high percentage of volatile matter and only a lowpercentage of cementA ing value. rlhis light bitumen has'aslits greatestasset, the ahilit \j to suppress dust, but; is of little value inpreserving the roadway and renderinglhesame wear-resisting. In fact. ithas been found that it often happens that considerable disintegrationtakes place in the portion of the roadwa)Y treated vwith lightbituminous products, t'or thel rear# son that the lightoils-\'olat'ili'/.e and leave the. treated portion of the roadway in theform of a coating in which the natural bonding; or cementing values-'ofthe material are destroyed.

The present inventieni contemplates the use of both the heav v and lightbitiuniuous products in such a way as to combine their advantageousqualities` and to dispense with the above-named objectionable effectsinvolred in the. individual use oteach. After a great deal ofexperiment-uw. it has been found that the lighter materials may beutilized to great advantage when corructiy used in combination with theheavieuiuaterials. and a much better road surface produced than can beobtained by the imlividual use of either of the products. The presentinvent-ion. therefore, contemplates the treatv ment of the roadwaywhether the same be of concrete` bituminous macadam. sheet .as phalt.stone, gravel. or othe.` constriaftion, with a lighter grade of bitumenwhich penetrates the roadway and is not prevented from doing;f so by theexistence-ot' dust or foreign matter. At a suitable time after thetreatment of the roadwayv with the. lighter bitumen, a heavy bitumen isapplied. which firmly unites with the lighter bitumen. and is in thiswa)v bonded or cemented with the particles of the roadway. The lighterbit-ie men` therefore. serves as a priming' coat which permits theI useof the heavier bituminous products having wear-resistinpT and otherproperties notI possessed'by the lighter bituminous products. Thispriming coat ot li gliter bituminous products, therefore., serves theYsa me purpose as the primingcoat in painting wood or the like., whereitl is necessary to apply a. priming coat of thin paint before the woodor other surface treated will re-tv deep into the roadway, and it isretained there by the heavier surface bitumen, which has the followingbeneficiallaction upon the roadway. The lighter bitumen contains a 5great deal of volatile matter, but the heavier bituminous coating whichhas a low per-`v centage of volatile matter serves as a seal, andprevents the escape of the volatile matteis ofthe underlying coatingV oflight bituminous matter. As the volatile matters in the lighter bitumencannot escape, the tendency is for them to penetrate farther and fartherinto the roadway, and in so Y doing, a chemical action results impartinga. new life to the roadway, and a higher cementing value to the primingcoat than it originally possessed. The. disintegrating action caused bythe volatilization of the lighter bitumen is,'therefore, prevented, as

the heavier coating prevents escape of the volatile matter. The resultis that a hard and elastic road surface is produced which 4has-beenfound in practice. to be superior to all types of roadways treated bysimilar 25, methods. If a portion of the volatile matter so confinedbeneath the heavy bitumious 'coating works upward instead of downwardinto the roadway, it'will be absorbed by'thefinishing coat of heavybitumen and 3o act thereupon in a manner similar to what is commonlytermed a eut-back, that is tov say, it will make the heavy bitumen moreof a. liquid, and this chemical action will result in carrying theheavie'ror finishing T coat farther into the road surface, so thatcementive value may be utilized below fthe original` road surface. Thisaction takes place so slowly that practically none of the volatile oilsof the primingcoat are lost,

4o-whereas, if the lighter bitumen is used by itself Without the heavierfinishing coat, it loses over half of its lighter constituents byvolatilization within sixty to ninety days. In carrying out the method,it has been found desirable for the best results to firstl sweep theroad surface as free as possible from all loose material, and then apply`the lighter bitumen 'by any 'suitable means, the quantity applieddependingupon the ab- 50 'sorption qualities of the roadway. The

quantity applied should be limited to the amount that the road surfaceis capable of absorbing., In some instances, it may be desirable to thenapply a thin layer of sand,

stone screenings, or sweepings from the road or street surface, and openthe roadway to traffic and exposure to the elements. ,T he heaviercoating of bituminous material may then .be applied to the road surface,butv preferably the application of the heavier' bitumen is made justafter the application of,the'priming coat of lighter bitumen. The secondcoat of heavier bituminous material may, if desired. be covered with alayer of either sand, fine gravel, or crushed stone.

The lighter bitumen not only` serves to penetrate into the body ot' theroadway, and thereby act as a priming coat. forthehean'ier bitumen, butalso produces other beneficial results. due to the fact that itslvolatile matters are confined within the roadway by the 'heavierbituminous finishing coat. The. heavier bituminous coating which wouldnot be bonded and-firmly united with the roadway., if it were not forthe relatively light priming coat, produces Athe elastic wear-resisting.sm-face, as the. heavier bituminous products possess the cementing anducar-resisting qualities which the lighter products do not possess, andwhich 5 it is essential that the top dressing should possess. 'lfhereis, therefore` an intimate co` operation between the two layers ofbituminous material, as each serves to permit the use of' the other, andwhen usedinA combi- 8 nation. their beneficial characteristics areretained, whereas the disadvantages accompanying the individual use ofeither of the materials independent of the other are overcome. Y 9 Inthe construction Qof penetration macf adam" roadways, after a layervofcoarse stone has been applied and rolled, and then a wearing surface ofstone applied to the first layer and rolled, it has been .the cus- 9 tomto apply a very heavy binder which required heating to a temperature offrom 300o to `l0()o F. Obviously, a binder requiring such a highheat-ing -soon thickens and the thin film'of dirt which necearily 'lq"remains onthe surface of the broken stone will act as a separator toprevent a union between the heavy `binder and the stone. This objectionis overcome by the present method, as the `broken stone may first, be 1(treated with the penetrating and priming coat of light. and unhea'tedbitumen which unites with the stone and prepares the same for -receivingthe heavy heated bitumen, which latter will then firmly unite with the1] primingl bitumen, and' hence the broken stone.

The accompanying dia-wing illustrates in transverse vertical section, 'aportion of a water-bound macadam roadway construct- 1; ed in accordance.with my improved method. This type of roadway is illustrated merely for'exemplary purposes, it being-undef-- stood that the method is applicableto many other types. 1g

The portion of the road-bed indicated at A shows the condition of thesame before treatment. That portion indicated at B has had the abovedescribed priming coat applied thereto, thc material of the ,priming 13coat being represented at 1. Due to 'the high penetrating-value of thematerial of the priming coat, it is readily absorbed by the surface ofthe roadway` as above stated. That portion of the road-bed indicated at'1l C shows the condition of the saine after the application of the,heavier bitiiminous coating :i which, as indicated in the drawing.'`firmly adheres to the roaddied on account of the, provision of thepriming coat.

The heroinbefore described cutting-back aetion of the priming coat 1 onthe heavier bituminous coating 2 and the consequent carrying otI aportion of the heavier eoating down into the heart of the roadbeii isropH resented in the drawing in section C", ln this. part oi' thedrawingv` it will be noted that the portion of the toi,l` Coatingeutbark by the primingr roat rarried b v the prix ing coat deep into theheart ol' tin road-taak where its eementive value may be utilized Thisis ay result oi the retention of the gases or volatile matter in theroad-bed by the hemier coating and the oonSequent cuttingn bark actionwhich increases the penetrating value ofl a portion of' the heaviercoating, and, therefore, the priming!` coat and the cutting-back portionof the heavier coat penetrate, deep into the road wasv. as illustratedin the drawing and as hereinbeire deSeribed.

1. The method of treatin;r road lief-is which consista in applying: tothe road ,aar-` fare a penetrating` and primingT coat of' lightbitmninous substance containing a ll rge per# eentagge ofi1 volatilematt-:fra eapalit: of Slow difi'usion, and thon before the volatilematters eL-Seape. appiying a coat of heavier bituminous substancecapable of confining and retaining the volatile, matters in the roadlied, the priming,r Coat being capable of binding the top coat to theroad surface and of' gradually cutting back the saine to utilize itscementi ve value below the original road surface. l

The method of treating road-beds which consists in first removing theloose dust from the road surface, applying to the ele-ined road surfacea penetrating and priming eoat of light bituminous Substance eontaininga large percentage of volatile .matters capable of slow diffusion, andthen before the volatile matters escape, applying a coat of heavierbituminous Substance oapable of confining,T and retaining the. volatilematters in the road bed, the priming coat beingr capable of binding thetop coat to the :road surface and of gradu iy cutting back the. same toutilize its cementive value below the original road surface. t

ln testimony whereof I affix my signature, .in presence of twowitnesses.

SAM EVERETT FINLEY. "ivritnesses:

H. F. SMITH, Hoon Umswiimi.

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